1. Field of the Invention
This invention is concerned with the manufacture of light olefin hydrocarbons from lower alcohols on their ethers. It is particularly concerned with the catalytic conversion of such alcohols and ethers selectively to mixtures of olefins having up to five carbon atoms. In another aspect, this invention is concerned with a novel catalytic process especially effective for the substantially complete conversion of methanol and/or dimethyl ether to a hydrocarbon mixture characterized by a predominance of olefins.
2. Description of the Prior Art
A remarkable growth in the production of synthetic fibers, plastics and rubber has taken place in recent decades. This growth, to a very large extent, has been supported and encouraged by an expanding supply of inexpensive petrochemical raw materials such as ethylene, propylene, and other, four and five carbon olefins. Side by side with this remarkable development, there has been an increasing demand for alkylate, made by reacting olefins with isobutane, for use as a high octane gasoline component. Environmental factors which limit the lead content of gasoline are likely to aggravate the need for alkylate.
Burgeoning demand for olefins, particularly ethylene, propylene and butenes, has of course led to periods of shortage, either due to short supply of suitable feedstocks or to limited processing capacity. In any case, it would appear desirable to provide efficient means for converting raw materials other than petroleum to olefins. The dehydration of alcohols, particularly ethanol to ethylene, by catalytic contact with the hydrogen exchanged form of mordenite is disclosed in U.S. Pat. No. 3,244,766 issued Apr. 5, 1966.
The production of olefins from methanol and dimethyl ether by limited conversion with HZSM-5 zeolite catalyst is described in copending U.S. patent application Ser. No. 537,043 filed Dec. 27, 1974, and now abandoned.
The use of a hydrocarbon diluent to dissipate exothermic heat in a two-stage conversion of methanol to gasoline is described in U.S. Pat. No. 3,931,349 issued Jan. 6, 1976 to Kuo.
A two-stage conversion of methanol to olefins and to gasoline which employs a tubular reactor for the second stage is described in U.S. patent application Ser. No. 496,434 filed Aug. 9, 1974 and now abandoned.